Investigation of specific heat and latent heat enhancement in hydrate salt based TiO2 nanofluid phase change material

In this study, the enhancements of specific heat and latent heat of inorganic hydrate salt based nanofluid phase change material were reported. The samples were prepared by incorporating TiO2 nanoparticles with different mass fractions (0.1, 0.3, and 0.5 wt%) into the eutectic hydrate salt (EHS). The phase change enthalpy and specific heat capacity were measured by differential scanning calorimeter (DSC). The results showed that the loading of 0.3 wt% TiO2 nanoparticles can increase specific heat by up to 83.5% and latent heat up to 6.4%. Moreover, the optical microscopy on crystal configuration confirmed the increase of solid specific heat and the corresponding mechanism. The interaction between EHS and TiO2 nanoparticles, which was responsible for elevation of phase change temperature, was revealed by Raman spectra. The chemical thermodynamics gave an explanation for latent heat improvement. These findings suggested that hydrate salt based TiO2 nanofluid offered a promising route for the achievement of high heat energy storage targets of hydrate salt phase change materials.